Tube construction



Dec. 30, 1947.

c. M. WALKER ETAL TUBE CONSTRUCTION Filed May 23, 1945 130 5- CHARLES MI MLmE/Q 41w m/I/WEZif/WU 0 154 ity to each other.

Patented Dec. 30, 1947 UNITED STA S PTENT OFFICE TUBE CONSTRUCTION Application May 23, 1945, Serial No. 595,310

3 Claims.

The present invention relates to electron-discharge tubes, and more particularly to those of smaller size, such as are used in pocket radios, hearing aid devices and the like.

In these very small tubes the space available for the electrode assembly is necessarily restricted, requiring that the elements of the electrode assembly be mounted in relatively close proxim- This reduces the amount of insulating material separating said elements and correspondingly weakens the structure. It also reduces the leakage paths between said elements. This is particularly true if the tube be of the vacuum, multi-electrode type.

One of the objects of the present invention is to provide a novel pattern or arrangement of the elements referred to, more particularly of the grid side rods, whereby the amount of insulating material separating said elements and the leak: age paths is materially increased.

These objects of the present invention and such other aims and objects thereof as may hereinafter appear will be best understood from the following description, taken in connection with the accompanying drawing, of a tube incorporating one illustrative embodiment of the invention.

In the drawing:

Fig. 1 is a longitudinal section on line II of Fig. 3, of a tube incorporating one illustrative embodiment of the invention on a greatly enlarged scale;

Fig. 2 is a longitudinal section on broken line 22 of Fig. 1;

Fig. 3 is a cross-section of Fig. 1 on line 3--3; and

Fig. 4 is a top plan view of the lower spacing member and associate parts showing a variation in the pattern of the grid side rods.

The tube illustrated in the drawing illustratively consists of a pentode, and comprises an envelope 2 of glass or other suitable material which may be of generally ellipsoidal shape in crosssection. The electrode assembly comprises an anode consisting of two parallel plates 4 and 6, a filamentary cathode 8 and a plurality of grids, I0, I2 and I4 interposed between said cathode and said anode plates 4 and 6. Upper and lower insulating spacing members It and I8, viewing Fig. 1, preferably of mica, provide adequate support and proper spacing for the electrodes. A plurality of resilient projections 20 are provided suitably spaced around the edges of said spacing members, said projections resiliently engaging the inner wall of said envelope 2.

Said anode plates 4 and 6 are each mounted suitable material.

upon a U-shaped frame 22 of nickel wire or other Each of said frames 22 is shaped to provide a straight top portion 24 and a pair of depending side arms 26 and 28. In assembling the tube, the ends of each of said side arms 26 and 28 are inserted through perforations in said upper spacing member I5 and the top of said frame 22 is pushed down until its straight top portion 24 rests upon the top of said upper spacing member I6. One of said anode plates is then welded to the side arms of each of said frames 22 with the upper end of each anode plate engaging the under side of said upper spacing member I6. Said anode plates may each be formed with grooved side edges, as shown at 30, Fig. 3, more readily to receive the side arms 26 and 28. The side arms 26 and 2B of each of frames 22 are then inserted through perforations in the lower spacing member I8, which is thus assembled in place upon the anode structure. A double arm anode bracket 32 is then welded to the lower ends of each of the side arms 28. Each arm of said anode bracket 32 is provided with a pair of ears 34 which engage the lower side of the insulating spacing member I8. In this way the anode assembly is completed with the two anode plates 4 and 6 electrically connected and securely fastened in place on the insulating spacing members I6 and I8.

The grids I0, I2 and I4 are wound and supported upon grid side rods 36-36, 3838 and 40-40 respectively. (See Fig. 3.) These grid side rods likewise project through perforations in the upper spacing member I6 and through correspondingly positioned and spaced perforations in the lower spacing member I8. The novel arrangement of these three sets of grid side rods and of the perforations through which they are threaded in said spacing members, in accordance with the present invention, will be fully described below. In order to prevent motion of the grid I4 and its associated side rods 40 relative to said spacing members I6 and I8, a pair of tabs 42 is welded to one of said side rods 40, and a pair of tabs 44 is welded to the other of said side rods 40, all of said tabs engaging both the lower and the upper side of the spacing members I6 and I8. A getter 46 may be welded to a conductor 48 which in turn is welded to the upper end of one of said side rods 4!], the one shown at the right of Fig. l, for example.

The filamentary cathode 8 is connected at its upper end to a conducting spring 50 and at its lower end to a conducting cross-piece 52, (see Fig. 2) connected at its opposite ends to two plugs 54 riveted through said lower spacing member 18. Said filamentary cathode passes through two triangular slots formed, one in the upper and one in the lower spacing member, only the one in said lower spacing member being shown at 56, (see Figs. 3 and 4), and by the tension exerted thereon by said sprin 50, said filamentary cathode is maintained in the apexes of said two triangular slots.

A lead-in conductor 58 for the anode plates 4 and 6 is welded to the anode bracket 32, a lead-in conductor 60 for grid I2 is welded to one of the side rods 38 of said grid, the rod 38 at the right in Fig. 1, for example, a lead-in conductor 62 for the cathode is welded to the conducting cross-piece 52, a lead-in conductor 64 for grid 40 is welded to one of the side rods 36 of said grid, and a lead-in conductor 66 for the grid I4 is welded to one of the side rods 40 of said grid, the side rod 43 at the left of Fig. 1, for example. All of these lead-in conductors are sealed through a press 68 formed externally of the envelope 2 at the base of the latter. The electrode assembly is thus retained in place within said envelope 2 and the required external electrical connections are provided for the various electrodes.

Heretofore the grid side-rods have been arranged in a straight line coincident with the major transverse axis of the tube. This had the disadvantage of increasing the size of the tube and 0f crowding said side rods closer together thus reducing this amount of insulating material of the spacing members between said side rods, particularly in the tubes of the vacuum multi-electrode type, with which the present invention is more particularly concerned. This crowding of said rods decreased the insulation space between said rods and also decreased the leakage paths.

In accordance with the present invention the grid side rods are arranged in a pattern in which said side grid rods are more widely spaced from each other than heretofore, thus eliminating in great measure the above-mentioned objectionable features. In the present illustrative embodiment of the invention this is conveniently effected by arranging said side grid rods in a staggered pattern. Thus, referring to Fig. 4, it will be seen that while the side rods of grids l0 and M, which are quite widely separated from each other, remain in a straight line, the intermediate side rods of grid 12 are out of alignment with or staggered relatively to the side rods of said two grids l0 and 14, thus materially increasing the space between said side rods.

In Fig. 3 on the other hand it will be seen that the irregular arrangement of the grid side rods is increased by arranging the side rods of grid 14, as well as those of grid I2, out of alignment with the side rods of grid 10. The pattern could be 4 still further varied by arranging the side rods of grid 10 out of alignment with the major axis also.

Any suitable method may be used to obtain a grid with its two side rods upon opposite sides of the major axis of the grid; for example the grid may be wound with the rods in that position, or .it may be wound with the two rods upon said axis and the two rods then brought into position upon opposite sides of said axis by stretching 'or otherwise manipulating the structure.

We are aware that the present invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof, and we therefore desire the present description to be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the aforesaid description to indicate the scope of the invention.

What is claimed is:

1. An electron-discharge tube comprising an electrode assembly includinga plurality of coaxial flattened tubular grids whose major axes lie in a common plane, and side rods supporting said grids, the side rods of at least one grid being staggered in a predetermined pattern relatively to'the side rods of other grids.

2. An electron-discharge tube comprising a plurality of coaxial flattened tubular grids whose major axes lie in a common plane, side rods supporting said grids, insulating spacing members for said grids on said side rods, said spacing members being provided with perforations in a predetermined staggered pattern for insertion therethrough of said side rods, said perforations being of the same staggered pattern in each 01 said spacing members.

3. An electron-discharge tube comprising a plurality of coaxial flattened tubular grids whose major axes lie in a common plane, side rods supporting said grids, the side rods for at least one of said grids being disposed in a straight lineconnecting diametrically opposed points of said grids, and the side rods of at least one other of said grids being disposed upon opposite sides of said line.

CHARLES M. WALKER. JAMES RAYMOND EISAN. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date 

